Steeljrv.com

What are Steel Pipes?

Steel pipe is long, hollow tube that are used in the piping system to transport liquid, gas and sometimes solids.Divided into carbon structural steel pipe, low alloy structural steel pipe, alloy steel pipe and composite steel pipe according to the material; divided into conveying pipeline, engineering structure, thermal equipment, petrochemical industry, machinery manufacturing, geology according to the purpose For drilling, steel pipes for high-pressure equipment, etc.; according to the production process, it is divided into seamless steel pipe and welded steel pipe. The seamless steel pipe is divided into hot rolling and cold rolling (pulling). The welded steel pipe is divided into straight seam welded steel pipe and spiral seam welding.Steel pipes are not only used to transport fluids and powdered solids, exchange heat, manufacture mechanical parts and containers, but are also an economical steel. The use of steel pipes to manufacture building structure grids, pillars and mechanical supports can reduce weight, save 20-40% of metal, and achieve mechanized construction. The use of steel pipes to manufacture highway bridges not only saves steel and simplifies construction, but also greatly reduces the area of the protective coating and saves investment and maintenance costs.

Welded steel pipes are divided into furnace welded pipes, electric welding (resistance welded) pipes and automatic arc welded pipes due to different welding processes. Due to the different welding forms, they are divided into straight welded pipes and spiral welded pipes, because their end shapes are divided. It is a round welded pipe and a special-shaped (square, flat, etc.) welded pipe.

The welded steel pipe is formed by welding a steel plate rolled into a tubular shape by a seam or a spiral seam. In terms of the manufacturing method, it is further divided into a welded steel pipe for low-pressure fluid transportation, a spiral-welded electric steel pipe, a direct-wound welded steel pipe, an electric welded pipe, and the like. Seamless steel pipes can be used in liquid pressure pipes and gas pipes in various industries. Welded pipes can be used for water pipes, gas pipes, heating pipes, electrical pipes, etc.

Classified by connection

The steel pipe can be divided into the light pipe (the pipe end is not threaded) and the wire pipe (the pipe end is threaded) according to the pipe end connection mode.The wire tube is further divided into: ordinary car wire tube and tube end thickened wire tube.Thickened wire tube can also be divided into: outer thickening (with external thread), inner thickening (with internal thread) and inner and outer thickening (with internal and external thread) and other ground wire tubes.If the wire tube is threaded, it can be divided into: ordinary cylindrical or conical thread and special thread.In addition, according to the needs of users, the wire tube is generally equipped with a pipe joint delivery.

Classified by plating characteristics

The steel pipe can be divided into black tube (not plated) and plated coated tube according to the surface coating characteristics.The coated tubes are galvanized, aluminized, chrome-plated, aluminized, and other alloyed steel tubes.The coated tube has an outer coated tube, an inner coated tube, and an inner and outer coated tube. Commonly used coatings are plastic, epoxy, coal tar epoxy and various glass type anti-corrosive coatings. Galvanized pipes are further divided into KBG pipes, JDG pipes, threaded pipes, etc.

Tubes for thermal equipment. Such as general boiler boiling water pipe, superheated steam pipe, locomotive boiler superheat pipe, large pipe, small pipe, arch brick pipe and high temperature and high pressure boiler pipe.

Types of steel pipes

Straight seam steel pipe is a steel pipe whose weld is parallel to the longitudinal direction of the steel pipe. Usually divided into metric electric welded steel pipe, welded thin-walled pipe, transformer cooling oil pipe and so on. Straight seam welded pipe has simple production process, high production efficiency, low cost and rapid development. The strength of the spiral welded pipe is generally higher than that of the straight welded pipe. It is possible to produce a welded pipe with a large diameter by using a narrow blank, and it is also possible to produce a welded pipe having a different pipe diameter by using a blank of the same width. However, compared with the straight pipe of the same length, the weld length is increased by 30 to 100%, and the production speed is low.General welded pipe: Generally welded pipe is used to transport low pressure fluid. Made of Q195, Q215A, Q235A steel, Q235B carbon. Straight seam steel pipes are subjected to experiments such as water pressure, bending and flattening, and have certain requirements on the surface quality. Usually, the delivery length is 4-10 m, and the fixed length (or double rule) is often required. The specification of the welded pipe is expressed by the nominal diameter (mm or inch). The nominal diameter is different from the actual one. The welded pipe has two kinds of ordinary steel pipe and thick steel pipe according to the specified wall thickness. The steel pipe is divided into two types according to the pipe end and the thread.The welding process of submerged arc welded straight seam steel pipe is submerged arc welding technology, which uses filler welding and particle protection flux submerged arc. The caliber of the production can reach 1500mm. LSAW is the English abbreviation for submerged arc welded straight seam steel pipe. The production process of submerged arc welding straight seam steel pipe has JCOE molding technology and roll-formed submerged arc welding technology. When the diameter is large, it may be rolled with two steel plates, which will form a double weld. Standard GB/T3091-2008 low-pressure fluid steel pipe production standard, GB/T9711.1-2 -1997 oil and gas steel pipe production and use standards can be implemented, and can also implement the US API 5L pipeline steel pipe implementation standard. Production material: Q195A-Q345E; 245R; Q345QA-D; L245-L485; X42-X70. The pressure parameters are mainly 2ST/T, S is the yield strength, and T is the wall thickness. Submerged arc welding has been developed to have double-wire submerged arc welding and multi-wire submerged arc welding, and the efficiency is further improved.

Production process of straight seam steel pipe

According to the production process, straight seam steel pipes can be divided into high-frequency straight seam steel pipes and submerged arc welded straight seam steel pipes. Submerged arc welded straight seam steel pipes are further divided into UOE, RBE, JCOE steel pipes according to their different molding methods. The following describes the most common molding processes for high-frequency straight seam steel tubes and submerged arc welded straight seam steel tubes.Submerged arc welding process

Panel inspection: After the steel plate used to manufacture the large-diameter submerged arc welded straight seam steel pipe enters the production line, the whole board ultrasonic inspection is first carried out;

Milling edge: double-sided milling the two edges of the steel plate by the edge milling machine to achieve the required plate width, edge parallelism and groove shape;

Pre-bend: use the pre-bending machine to pre-bend the edge of the board so that the edge of the board has the required curvature;

Molding: On the JCO molding machine, half of the pre-bent steel plate is first stepped and pressed into a “J” shape, and the other half of the steel plate is also bent and pressed into a “C” shape, and finally an opening is formed. “O” shape

Expanding diameter: Expanding the full length of the submerged arc welded straight seam steel pipe to improve the dimensional accuracy of the steel pipe and improve the distribution of stress in the steel pipe;

Hydraulic test: The steel pipe after diameter expansion is tested on the hydraulic testing machine to ensure that the steel pipe meets the test pressure required by the standard. The machine has automatic recording and storage functions;

Chamfering: The steel pipe after passing the inspection shall be processed at the end of the pipe to achieve the required pipe end groove size;

Ultrasonic inspection II: Ultrasonic inspection is carried out again and again to check for defects that may occur after straightening and water pressure of straight seam welded steel pipes;

X-ray inspection II: X-ray industrial TV inspection and tube end weld filming of the steel pipe after the expansion and hydrostatic test;

Tube End Magnetic Particle Inspection: Perform this inspection to find tube end defects;

Anti-corrosion and coating: The qualified steel pipe is preserved and coated according to user requirements.

High frequency welding process

The straight seam welded steel pipe is obtained by winding a long strip of a certain specification into a round tube by a high frequency welding unit and welding the straight seam into a steel pipe. The shape of the steel tube may be circular or square or shaped, depending on the sizing rolling after welding. The materials of welded steel pipe are mainly low carbon steel and low alloy steel or other steel with σs≤300N/mm2 and σs≤500N/mm2. The production process of high-frequency welding of straight seam steel pipe is as follows:

High frequency weldingHigh-frequency welding is based on the principle of electromagnetic induction and the skin effect, proximity effect and eddy current effect of alternating charge in the conductor, so that the steel at the edge of the weld is locally heated to a molten state, and the extrusion of the roller causes the butt weld to achieve crystal indirect. In order to achieve the purpose of weld welding. High-frequency welding is a kind of induction welding (or pressure contact welding), which does not require weld filler, no welding splash, narrow welding heat affected zone, beautiful welding and good welding performance, so it is affected in the production of steel pipe. A wide range of applications.The high-frequency welding of the steel pipe is to use the skin effect and the proximity effect of the alternating current. After the steel (strip) is rolled and formed, a circular blank with a broken cross section is formed, and a tube is rotated near the center of the induction coil. Or a set of impeders (magnetic bars), the impedance forming an electromagnetic induction loop at the opening of the blank, and under the effect of the skin effect and the proximity effect, a strong and concentrated thermal effect is generated at the edge of the opening of the blank, so that the edge of the weld After rapidly heating to the temperature required for welding, the metal in the molten state is intergranularly bonded after being pressed by the pressure roller, and after cooling, a firm butt weld is formed.

A seamless steel pipe made of a single piece of metal and having no seams on its surface is called a seamless steel pipe. According to the production method, the seamless pipe is divided into a hot rolled pipe, a cold rolled pipe, a cold drawn pipe, an extruded pipe, a top pipe, and the like. According to the shape of the section, the seamless steel tube is divided into two types: a circular shape and a special shape. The shaped tube has a plurality of complicated shapes such as a square shape, an elliptical shape, a triangular shape, a hexagonal shape, a melon shape, a star shape, and a winged tube. The maximum diameter is 650mm and the minimum diameter is 0.3mm. Depending on the application, there are thick-walled tubes and thin-walled tubes. Seamless steel pipes are mainly used as petroleum geological drilling pipes, cracking pipes for petrochemicals, boiler tubes, bearing tubes, and high-precision structural steel tubes for automobiles, tractors, and aviation.

Production process of seamless steel pipe

1 Main production process of hot-rolled seamless steel pipe (△ main inspection process):

2 cold rolling (drawing) seamless steel pipe main production process:

Blank preparation → pickling lubrication → cold rolling (pull) → heat treatment → straightening → finishing → inspectionThe production process of general seamless steel pipe can be divided into cold drawing and hot rolling. The production process of cold rolled seamless steel pipe is generally more complicated than hot rolling. The pipe blank must first be rolled in three rolls. The sizing test, if the surface does not respond to the crack, the round tube is cut by a cutter and cut into a blank having a length of about one meter. Then enter the annealing process, the acidification should be acid-washed with acid liquid. When pickling, pay attention to whether there is a large amount of foaming on the surface. If there is a large amount of foaming, the quality of the steel pipe will not reach the corresponding standard. The appearance of cold-rolled seamless steel pipe is shorter than that of hot-rolled seamless steel pipe. The wall thickness of cold-rolled seamless steel pipe is generally smaller than that of hot-rolled seamless steel pipe, but the surface looks brighter than thick-walled seamless steel pipe, and the surface is not too More rough, not too many burrs in the caliber.The delivery status of the hot-rolled seamless steel pipe is generally delivered after the heat treatment in the hot rolled state. After the quality inspection, the hot-rolled seamless steel pipe is subjected to strict manual selection by the staff. After the quality inspection, the surface is oiled, followed by multiple cold drawing experiments, and the perforation experiment is performed after the hot rolling process. If the perforation is too large, straightening correction is required. After straightening, the conveyor is sent to the flaw detector for flaw detection experiments. Finally, the label is placed, the specifications are arranged, and then placed in the warehouse.Round tube billet → heating → perforation → three-roll cross-rolling, continuous rolling or extrusion → pipe removal → sizing (or reducing diameter) → cooling → straightening → hydraulic test (or flaw detection) → marking → storage seamless steel pipe The steel tube or the solid tube blank is made into a capillary tube by perforation, and then is formed by hot rolling, cold rolling or cold drawing. The specifications of the seamless steel pipe are expressed by the outer diameter * wall thickness in millimeters.The outer diameter of hot-rolled seamless pipe is generally larger than 32mm, the wall thickness is 2.5-200mm, the outer diameter of cold-rolled seamless steel pipe can reach 6mm, the wall thickness can be 0.25mm, the outer diameter of thin-walled pipe can reach 5mm, the wall thickness is less than 0.25mm, cold Rolling is more accurate than hot rolling.Generally, the seamless steel pipe is formed by hot-rolled or cold-rolled low-alloy structural steels such as 10, 20, 30, 35, 45, etc., such as 16Mn and 5MnV, or 40Cr, 30CrMnSi, 45Mn2, 40MnB, and the like. Seamless pipes made of low carbon steel such as 10 and 20 are mainly used for fluid conveying pipes. 45, 40Cr and other medium carbon steel seamless pipes are used to make mechanical parts, such as the force parts of automobiles and tractors. Generally, seamless steel pipes are required to ensure strength and flattening test. The hot rolled steel pipe is delivered in a hot rolled state or a heat treated state; the cold rolling is delivered in a heat treated state.Hot rolling, as the name suggests, has a high temperature of the rolled piece, so the deformation resistance is small and a large amount of deformation can be achieved. Taking the rolling of the steel sheet as an example, the thickness of the continuous casting blank is generally about 230 mm, and after rough rolling and finish rolling, the final thickness is 1 to 20 mm. At the same time, due to the small width-to-thickness ratio of the steel plate, the dimensional accuracy requirement is relatively low, and the shape problem is not easy to occur, and the convexity is mainly controlled. For the organization, it is generally achieved by controlled rolling and controlled cooling, that is, controlling the rolling temperature and finishing temperature of the finishing rolling. Round billet → heating → perforation → heading → annealing → pickling → oiling (copper plating) → Multi-pass cold drawing (cold rolling) → blank tube → heat treatment → straightening → hydraulic pressure test (inspection) → marking → storage.

Precision steel pipe is a kind of high-precision steel pipe material after cold drawing or hot rolling. Because the inner and outer walls of precision steel pipes have no oxidation layer, high pressure and no leakage, high precision, high smoothness, no deformation of cold bending, flaring, flattening without cracks, etc., they are mainly used to produce pneumatic or hydraulic components, such as cylinders or The cylinder can be a seamless tube or a welded tube.Precision steel pipe production processThe production process of precision steel pipes is the same as the ordinary seamless pipe, which is the procedure of the final pickling and cold rolling.

Galvanized steel pipes are classified into cold-galvanized steel pipes and hot-dip galvanized steel pipes, and cold-galvanized steel pipes have been banned. The galvanized pipe is used as a water pipe. After a few years of use, a large amount of rust is generated in the pipe. The yellow water that flows out not only pollutes the sanitary ware, but also is mixed with bacteria that grow on the inner wall of the slick. The rust causes the heavy metal content in the water to be too high, which seriously endangers the health of the human body.

Sizes and dimensions of Steel pipe

Generally, steel pipe sizes and steel pipe dimensions is by outside diameter, wall thickness and weight per meter. there is figure to show the steel pipe sizes list.

Out diameter

Wall Thickness

Weight(kg/m)

Out diameter

Wall Thickness

Weight(kg/m)

Out diameter

Wall Thickness

Weight(kg/m)

32

3

2.15

159

4

15.29

820

10

199.75

32

4

2.76

159

5

18.99

820

12

239.10

32

5

3.33

159

6

22.64

820

14

278.26

38

3

2.56

219

4

21.21

920

8

179.92

38

4

3.54

219

5

26.39

920

9

202.19

38

5

4.07

219

6

31.52

920

10

224.41

42

3

2.86

219

7

36.60

920

12

268.70

42

4

3.75

219

8

41.63

920

14

312.79

42

5

4.56

273

5

33.04

1020

8

199.65

45

3

3.11

273

6

39.51

1020

9

224.38

45

4

4.04

273

7

45.92

1020

10

249.07

45

5

4.93

273

8

52.28

1020

12

298.29

50

3

3.48

325

5

39.46

1020

14

347.41

50

4

4.54

325

6

47.20

1020

16

396.14

50

5

5.55

325

7

54.89

1020

18

444.77

54

3

3.77

325

8

62.54

1220

10

298.39

54

4

4.93

325

9

70.13

1220

12

357.47

54

5

6.04

325

10

77.68

1220

14

416.36

57

3

3.99

377

6

54.89

1220

16

475.05

57

4

5.23

377

7

63.87

1420

12

416.66

57

5

6.41

377

8

72.80

1420

14

485.41

60

3

4.22

377

9

81.67

1420

16

553.96

60

4

5.52

377

10

90.50

1620

12

475.84

60

5

6.78

426

6

62.14

1620

14

554.46

68

3

4.81

426

7

72.33

1620

16

632.87

68

4

6.31

426

8

82.46

1620

18

711.10

68

5

7.77

426

9

92.55

1820

12

535.02

70

3

4.96

426

10

102.59

1820

14

623.50

70

4

6.51

480

6

70.13

1820

16

711.79

70

5

8.01

480

7

81.65

1820

18

799.87

73

3

5.18

480

8

93.12

1820

20

877.76

73

4

6.81

480

9

104.53

2020

14

692.55

73

5

8.39

480

10

115.90

2020

16

790.70

76

3

5.40

529

7

90.11

2020

18

888.65

76

4

7.10

529

8

102.78

2020

20

986.40

76

5

8.76

529

9

115.41

2020

22

1083.95

89

3

6.36

529

10

127.99

2220

16

869.61

89

4

8.39

630

8

122.71

2220

18

977.42

89

5

10.36

630

9

137.82

2220

22

1192.46

108

3

7.77

630

10

152.89

2220

24

1299.68

108

4

10.26

720

8

140.46

2420

16

948.52

108

5

12.70

720

9

157.80

2420

18

1066.20

133

3

11.18

720

10

175.09

2420

20

1183.68

133

4

14.26

820

8

160.19

2420

22

1330.96

133

5

17.29

820

9

179.99

2420

24

1418.05

Uses of steel pipes

Steel pipes are used in different applications such as :

Water Pipes

Steel Casing Pipes

Sewage Pipes

Structural Steel Pipes

Industrial Steel Pipes

Steel Scaffolding Pipes

Oil & Gas Pipes

Three points for steel pipe inspection process

No matter seamless steel pipe or welded pipeline, we should have check methods for the final products in order to guarantee the quality. Here are three main points for the tube’s inspection process.There is no cracks, lack of fusion, porosity, slag and spatter for the welded joint’s surface. As these drawbacks would finally have big influence for the good quality of a steel tube. Pipeline design temperature is below -29 degrees, fan ruler of hardened stainless steel and alloy steel pipes tend to be larger weld surface, without undercut.Nondestructive test is necessary on the pipe’s surface. Different steel pipe with various functions should take different pressure taking. Thus, magnetic iron pipe should be used in magnetic particle testing; non-ferromagnetic steel should be used in penetration testing.Ray inspection and ultrasonic testing. Ray inspection and ultrasonic testing is the main target of the butt joint pressure pipe and pipe fittings for butt joints.

How to choose steel pipes

Choose a steel pipe according to its working pressure

Short-distance and long distance pipeline, no matter seamless steel pipe for oil and gas transportation, or welded one for water transportation, would have great difference on choosing.To some extent, working pressure and diameter would decide the pipeline’s design of framework technical parameters.First of all, working pressure directly determines the number of pumping stations and compressor stations, steel consumption in the power station unit and piping.Working pressure on the economy and security of the pipeline project is the first. Working pressure is an important part of the design of oil and gas pipelines, the technical and economic conditions of its great influence on the pipeline, the pipeline operating pressure is not too high; optimum working pressure gas pipeline and gas pipeline construction investment and operating costs related to; generally, the high pressure tends to work best value.

Tips to Choose Good Quality Seamless Steel Pipes

As for good quality seamless steel pipes, its cross section should be smooth and even. If you see there is burr or uneven cross section, do not pick up these defective seamless steel pipes.

You need to know the percent of impurities. Weight the pipes and measure its density. If it is low density, light seamless steel pipes will be poor quality.

Check trademark. There will be standard trademark and words on seamless steel pipe from good quality seamless steel pipes manufacturers.

Check the shape of seamless steel pipes. As for poor quality pipes, you will find oval shape on the side of it.

How to Choose Quality 304 Stainless Steel Pipes

Firstly, before the selection of 304 stainless steel pipe, you should consider its usage and environment. We often use weld pipe for decoration, seamless steel pipes for fluid delivery, sanitary stainless steel pipes for medical or kitchen, thick-walled steel pipes for pressure. 200 series material can be used for indoors and 304 can be used for outdoors. In the alkaline or coastal areas, level over 316 materials are generally used.Secondly, the selection of 304 stainless steel pipes must be standard. From the price analysis, if the 304 stainless steel pipe is lower than 301, then you should carefully identify. It is likely replaced by other materials. Recognize whether the surface has the material words “304”, and check the quality certificate from manufacturer. Using acid reagent for test, 304 stainless steel pipes will not change color after 30 seconds but 201 will getting black. If you need to purchase in bulk, you’d better take some samples to the national authority for component testing.Thirdly, observe the outer surface and inner wall color if it is bright and smooth, the thickness is uniform or rough. Generally, welded pipe need not to check. However, seamless steel pipe is manufactured by cold drawn or hot rolling, the surface is to crack with improper operation in the production process. If the surface is rough, it generally means seamless steel pipes have not been polished.

There are more and more people choose to use carbon steel pipe in the construction. Why? Next, yaang will show you some advantages of carbon steel pipe for all of you.A.Safe and durableWe all know that steel is a frequently-used material because it is durable and safe. Since steel is non-combustible and makes it harder for fire to spread, it is good to use when building homes. Carbon steel pipe is highly resistant to shock and vibration. Fluctuating water pressure or shock pressure from a water hammer have little effect on steel. And carbon steel pipe is practically unbreakable in transport and service, and for this reason it is okay to lay water mains under roadways.B. Environmental protectionUsing steel for pipes is not only safer for people, but it is safer for the earth. Steel can be recycled. Each year, about 70 percent of all steel is recycled in North America, more than paper, aluminum, plastic and glass combined. Steel products can be recycled over and over without losing any strength. Almost half the world’s steel is produced in electric plants that use recycled scraps and generate no CO2 emissions.C. Cost-EffectiveFor any given pressure, carbon steel pipes can be made much thinner than pipes made from other materials, so they have a greater carrying capacity than pipes of other materials with the same diameter. The unmatched strength of steel piping increases longevity and reduces the need for replacement and repairs.Its versatility also makes it cost-effective. Yaang can make pipes in many dimensions, from less than an inch to over five feet. They can be bent and wrought to curve and fit anywhere they need to be. Joints, valves and other fittings are widely available at good prices.

How to Choose the SSAW Carbon Steel Pipe Manufacturer

Usage of SSAW carbon steel pipe is relatively high, the application is very wide, it should be how to choose before in the selection to pay attention to quality.The first method is a more professional detection method, that is, by the strength of the pressure vessel to be detected. Commonly, we use atmospheric pressure and water pressure to detect, in this way can detect the working conditions of the SSAW carbon steel pipe in the pressure working environment, but also to detect the tightness of the spiral steel pipe, generally take the atmospheric pressure detection, because such security Relatively high, and if the water vapor pressure through the test, then the need to remove the spiral pipe after the water, too much trouble.The second method is also relatively simple, that is, through the surface of observation. With the naked eye found in the spiral steel pipe in the welding and size of the problem, if necessary, you can also use the standard sample and the products to be compared to find the problem. In general, formal steel pipe company in the production is relatively perfect, on the other hand to beat the metal pipe, if the sound is very crisp and the echo is not very dirty, then the name is the latest selection of steel pipe, rather than scrap steel recycling.These two methods are commonly used, we can choose a way to test, more secure way is the best to the regular manufacturers, can reduce the use of the process of abuse.